For those who already own the Shadowgrounds games, you will be happy to know that the GNU/Linux clients have been improved and now you should no longer have crashes (and if you still do, they will fix it).
Also Trine2 is coming to GNU/Linux as well (but it’s not part of this bundle), more info in the little chat I’ve had with Lauri from Frozenbyte :

LGN: Hi !Lauri/Frozenbyte: Hello!LGN: Does the bugs in SG and SG:S have been fixed ? (the bugs that crashes the game in some levels)Lauri/Frozenbyte: It’s been improved for the Mac/GNU/Linux ports
but we haven’t compiled new Windows versions yet, but will do that “soonish”
all updates will come to Steam and other versions as well, we’ve also added physics to original SG.LGN: I bought those games from LGP, so I’m talking about the GNU/Linux version – but as I understand those bugs were present in the original versionLauri/Frozenbyte: GNU/Linux version has been updated for this bundleLGN: So the crashes are fixed ?Lauri/Frozenbyte: In our tests they didn’t crash at all
but of course when 1000’s of more people join in there might be found new issues, which we will fix.
any bugs will be fixed by the original porting team.LGN: I remember reading in your forums long time ago that u know about the crashing bugs but do not know why it happens, you gave some save games to “bypass” it.Lauri/Frozenbyte: Yeah I think that was windows version
with recent improvement there was discovered and fixed some crashes, but it’s old codebase so I can’t guarantee it’s perfect, but we will work out any bugs discoveredLGN: Thats’ great cuz there was a mission in SG:S that kept crashing for me – now I hope to be able to finish it , btw who made the GNU/Linux port this time ?Lauri/Frozenbyte:It’s the same team who did the original, but they have now learned a lot more 🙂
they are called Alternative GamesLGN: I thought it’s another company with some old members
btw why there is a Windows only game in the bundle ?Lauri/Frozenbyte: They have changed their name but it’s the same people 🙂
it’s a prototype which we were not able to port in time
but the guys are working on it, so GNU/Linux/mac should be coming, it also includes source code so if someone is really keen to get it right now it’s possible 🙂LGN: Nice, I’ll definitely contribute for the third time 😀Lauri/Frozenbyte: Thank you! 🙂LGN: although I already have most of the games, as with the second bundleLauri/Frozenbyte: Well, pay for only the ones you don’t have .. the lowest possible is 0.01 usd 🙂LGN: But you deserve it for supporting GNU/LinuxLauri/Frozenbyte:It’s really up to you.LGN: I’m not a cheapass 😉Lauri/Frozenbyte: hehe 🙂LGN: Any new projects you porting to GNU/Linux ?Lauri/Frozenbyte: We’ve aiming to bring all of our games to GNU/Linux as well
so Trine 2, once completed, should be coming to GNU/Linux also, and of course Splot, which is also in the bundleLGN: Thanks you very much for this wonderful bundle !

Pay what you want. If you bought these four games separately, it would cost around $50 but we’re letting you set the price!
All of the games work great on Mac, Windows, and GNU/Linux.

We don’t use DRM. When you buy these games, they are yours. Feel free to play them without an internet connection, back them up, and install them on all of your Macs and PCs freely. There is no time-limit on your downloads.

You can support charity. Choose exactly how your purchase is divided: Between Frozenbyte, the Electronic Frontier Foundation, or the Child’s Play Charity. Also, if you like this deal, a tip to the Humble Bundle itself would be much appreciated!

So go ahead and Pay What YOU Want for this bundle, those games are extremely fun and worth the original money.

Up till this moment the GNU/Linux users are as usually ahead of everyone with an average of ~$12.
You have two weeks to participate and improve the GNU/Linux users contributions to the bundle so the developers will port more games to GNU/Linux.

Already bought them right as they were available. Was within the first 1k customers. I already own SG and SG:S. Jack Claw looks nice, but no Linux client yet. Thought about looking at the source, but I don’t really have the time right now, so I will have to wait till they ported it.
I’ve been waiting for Trine for a pretty long time though, so I payed 30$, to support the future of my one and only platform. (essentially only for Trine at the current time.)

Same here…
I already bought SG and SG:S from LGP, but SG:S always crashed at some level which makes it impassible- now they say it’s been fixed.
Also I’ve participated in the beta of Trine and it’s a very fun and good game, like all FrozenByte games.
So I also gave $30 for the case (now that I’ve finally found a job after many months…).